A solution, such as a sample, reagent, buffer, or washing solution, used for a capillary electrophoresis apparatus is reserved in a container hermetically sealed with an evaporation-preventing membrane. Capillaries are brought into contact with a solution in a container through bores provided on an evaporation-preventing membrane.
An evaporation-preventing membrane is made of an elastic material. When capillaries are passing through bores on an evaporation-preventing membrane, the bores are contracted due to the elastic force, and the evaporation-preventing membrane hermetically seals the capillary peripheries. When capillaries are passed through bores on the evaporation-preventing membrane, a driving force that forces the capillaries into the bores against the friction between the capillaries and bores is necessary. When capillaries are withdrawn from bores on the evaporation-preventing membrane, a driving force that withdraws the capillaries against the friction is necessary. When capillaries are withdrawn from bores on the evaporation-preventing membrane, the evaporation-preventing membrane is raised up apart from the container due to the friction between capillaries and bores. When such friction is strong, not only the evaporation-preventing membrane but also the container may be raised up.
In order to overcome such drawbackes, the capillary electrophoresis apparatus described in WO 2002/079773 (A1) involves the use of a stripper. By pressing down the evaporation-preventing membrane with a stripper, the evaporation-preventing membrane or container is prevented from being raised when withdrawing capillaries from the evaporation-preventing membrane.
Engagement sections are provided in the capillary electrophoresis apparatus described in JP Patent (Kokai) No. 2008-298659 A so as to prevent the evaporation-preventing membrane from being detached from various sample-containing containers, such as buffer containers, or to prevent a container from being detached from the container holder, even when capillaries are inserted or withdrawn.